Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 315 AM EST Tue Mar 07 2017 Valid 12Z Tue Mar 07 2017 - 12Z Thu Mar 09 2017 ...Another round of heavy snow is expected across the Pacific Northwest and inland to the Northern Rockies over the next couple days... ...A line of showers and thunderstorms will continue to push across the eastern U.S. today... ...Snow showers are possible for the northern Upper Mississippi Valley and Upper Great Lakes today and Wednesday... As has been the pattern, as one low pressure exits the Pacific Northwest, another one approaches. This next incoming low is expected to make landfall by this evening, with a surge of moist air pushing inland ahead of the system. As such, expect yet another round of heavy rain along the coast of Northern California, Washington, and Oregon. Rain will change to snow as it moves inland and into the higher terrain. The snow will be heavy at times, persisting over the next couple of days in many locations. Winter Storm Warnings and Advisories are in effect from the Cascades eastward into the Northern Rockies for the incoming snow. Meanwhile, a robust surface low pressure system is still driving the weather for much of the eastern U.S. This low is expected to slowly move northeast along the Quebec/Manitoba line today and tonight, reaching the Hudson Bay by Wednesday. A potent cold front extending southward from this low will continue to sweep eastward, impacting areas east of the Mississippi River and near the Gulf of Mexico today. Widespread rain and thunderstorms will be the main concern ahead of the cold front. The Storm Prediction Center has outlined a portion of the lower Mississippi and Tennessee Valleys as being in a slight risk for severe thunderstorms through today, and an area extending from Eastern Texas into the northern Tennessee Valley in a marginal risk. Please refer to the Storm Prediction Center for additional information on the threat for severe weather. Another reinforcing cold front will protrude southward from Canada on the backside of the low. This will result in a strong push of arctic air into the north central U.S. Lingering moisture across the region will collide with this cold air to produce snow showers along the Canada border in the Upper Mississippi Valley today, and in the Upper Great Lakes tonight and Wednesday. Wix Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php